Stabilized 1,1,1-trichloroethane composition

ABSTRACT

1. A STABILIZED COMPOSITION CONSISTING ESSENTIALLY OF 1,1,1-TRICHLOROETHANE AND, AS A STABILIZER THEREFOR, 0.15.0 WEIGHT PERCENT OF 1,4-DIOXANE 0.01-1.0 WEIGHT PERCENT OF ACRYLONITRILE 0.05-3.0 WEIGHT PERCENT OF ETHYL ACETTE AND 0.1-3.0 WEIGHT PERCENT OF NITROMETHANE.

United States Patent O 3,848,004 STABILIZED 1,1,1-TRICHLOROETHANE COMPOSITION Seiichi Katsuragawa, Saitama-ken, and Teruo Fujinaga, Yokohama, Japan, assignors to Central Glass Co., Ltd., Yamaguchi-ken, Japan No Drawing. Filed Dec. 21, 1971, Ser. No. 210,542 Claims priority, application Japan, Dec. 26, 1970,

45/118,604 7 Int. Cl. C07c 17/42 U.S. Cl. 260-652.5 R 2 Claims ABSTRACT OF THE DISCLOSURE A stabilized 1,1,1-trichloroethane composition containing 1,4-dioxane, acrylonitrile, an alkyl acetate and a nitroalkane.

BACKGROUND OF THE INVENTION This invention relates to a 1,1,1-trichloroethane composition which has been stabilized against metals.

For the reasons that as a solvent for oils such as cutting oils, machine oils, greases, etc., not only is its solvent power good, but it also is not inflammable and has lesser toxicity than the other chlorinated hydrocarbons, as well as the fact that it is not readily decomposed by either light or oxygen, 1,1,1-trichloroethane is widely used commercially as a degreasing solvent for cleaning metal products. However, when 1,1,1 trichloroethane comes into contact with metals, and especially aluminum, it reacts therewith very fast and is decomposed to form hydrochloric acid and a brown tany matter. Thus, it has been the usual practice to add various stabilizers to the 1,1,1- trichloroethane to inhibit this decomposition.

Various organic compounds are being added either singly or in combination to 1,1,1-trichloroethane as the stabilizer. However, when this stabilizer-containing 1,1,1- trichloroethane is used under harsh conditions, such as in steam cleaning and ultrasonic cleaning in contact with such metals as aluminum, iron, zinc and brass, it is difficult for it to provide results which are satisfactory. Also, the differences in the cleaning conditions at the different workships have an effect on the stability of 1,1,1-trichloroethane. For instance, the stability of 1,1,1-trichloroethane containing the same stabilizer will be influenced by such various conditions as the type and size of the cleaning machine, the method of heating, the class and size of the metals to be cleaned, the extent of the accumulation of the metallic scraps, the class of the cutting oil, the method of distillation and recovery, the number of cleansing times and the amount of admixed water.

In using 1,1,1-trichloroethane as a metal detergent, the admixture of water therein is not desirable, since this results in the hydrolysis of 1,1,1-trichloroethane. Especially, in a system in which aluminum and water are copresent the decomposition of 1,1,1-trichloroethane is accelerated. Therefore, the admixture of water in 1,1,1-trichloroethane is usually held to be most undesirable. However, as a. practical matter, when the cooling and condensation of the vapor of 1,1,1 trichloroethane takes place in the cooler of the steam cleaning machine, the moisture contained in the air also gradually condenses in the foregoing cooler until finally the water content of the 1,1,1-trichloroethane approaches the saturated state. Further, there are some cutting oils which are water-soluble, and when these are used in machining a metallic part, the result is an adherence of a small quantity of water to the machined part. Now, when this metallic part is cleansed with 1,1,1-trichloroethane, water gets admixtured therein. Since water enters the cleansing system in this manner, a great decrease in the stability of the 1,1,1-trichloroethane 3,848,004 Patented Nov. 12, 1974 takes place, with the consequence that either the decomposition of the 1,1,1-trichloroethane takes place or the surface of the metal becomes susceptible to rusting.

An object of the present invention is to provide a 1,1,1- trichloroethane composition which is stabilized to not only aluminum but also such other metals as iron, zinc and brass.

Another object of the invention is to provide a stabilized 1,1,1-trichloroethane composition which demonstrates an improved stability when used in a water-containing system.

SUMMARY OF THE INVENTION The present invention provides a stabilized 1,1,1-trichloroethane composition containing 1,4-dioxane, acrylonitrile, an alkyl acetate and a nitroalkane.

The stabilized 1,1,1-trichloroethane of the invention contains, based on the 1,1,1-chloroethane, 0.1-5.0 weight percent, and preferably 1-4 weight percent, of 1,4-dioxane, 0.01-1.0 weight percent, and preferably 0.1-0.5 weight percent of acrylonitrile, 0.05-30 weight percent, and preferably 0.1-1.0 weight percent, of an alkylacetate and 0.1-3.0 weight percent, and preferably 0.1-1.0 weight percent of a nitroalkane.

As the alkyl acetate, the alkyl acetates whose alkyl group contains 1-5 carbon atoms, e.g., methyl acetate, ethyl acetate and propyl are useable acetate, particularly preferred being ethyl acetate.

As the nitroalkane, a nitroalkane having an alkyl group of 1-3 carbon atoms, e.g., nitrornethane and nitroethane is suitable.

A small amount of a phenolic antioxidant may also be added to prevent the oxidative decomposition of the stabilizer.

For a further illustration of the invention the following examples are given. The test methods 1 and 2, which have been employed in the examples, will be described. The test method 1 is a heating-under-reflux corrosion test in which the conditions employed are similar to those in an actual cleansing machine. On the other hand, the test method 2 is a test for determining the corrosion that results from the hydrolysis of the 1,1,1-trichloroethane. In this case the test is carried out with a volume ratio of the 1,1,1-trichloroethane test liquid to Water of 1:1 and in a state in which a water layer is present above the 1,1,1- trichloroethane layer, i.e., in the state of a presence of a great excess of water (in actual practice the presence of Water in such a great amount cannot happen). This test is to determine the stability of the 1,1,1-trichloroethane composition of the present invention under such conditions. Since in a water-excess system, such as described, the migration of the stabilizer into the Water, the dissolution of the 1,1,1-trichloroethane into the water and the hydrolysis of the 1,1,1-trichloroethane take place, this can be regarded as being a method of testing the stability of 1,1,1-trichloroethane under harsh conditions from a different angle.

EXAMPLES Test method 1.-Heating-under-reflux corrosion test Three hundred-milliliter flasks each equipped with a reflux condenser are each charged with ml. of 1,1,1- trichloroethane test liquids containing the stabilizers indicated in Table 1 in the amounts indicated, following which 0.1 ml. of Water is added. Two aluminum test pieces (40 x 20 X 5 mm. in dimensions) Whose surface has been thoroughly polished are then placed inside each flask. One piece is placed in the test liquid and another similar test piece is suspended in the vapor phase. This flask is then dipped in an oil bath heated at C. and heating under reflux is carried out until the decomposition of the 1,1,1- trichloroethane takes place or for the prescribed period of time (50 hours). This is followed by cooling the test pieces to room temperature and observation of the state of corrosion. Further, to determine the extent of the decomposition of the test liquid, the pH of the liquid before and after the test is measured. The same test is also carried out on iron and brass. The results obtained are shown in Table 2.

In the table the symbol C) denotes that there was no corrosion, while the symbol A denotes either partial corrosion or loss of luster, and the symbol X denotes that the test piece was corroded.

Method of measuring the pH.

Fifty milliliter of the test liquid and 50 milliliters of pure water (pH 6.0) are placed in a separating funnel Test method 2.--'Ilest of corrosion by means of hydrolysis of 1, 1, 1 -trichloroethane The 1,1,1-trichloroethane test liquid and water are mixed in a volume ratio of 1:1, after which 150 ml. of the mixture are placed in a 200-ml. flask and, after thorough stirring for about one minute, is rested. Separation into a top and a bottom layer takes place. An aluminum test piece (dimensions 40 x 20 x 5 mm.) whose surface has been thoroughly polished is then dipped in the bottom 1,1,1-trichloroethane layer and placed in a constant temperature tank maintained at 50 C. for 5 hours. After the passage of this period of time, the state of corrosion of the aluminum test piece is observed. The results are shown in Table 3.

TABLE 3.TEST OF CORROSION BY MEANS OF HYDROLYSIS Composition of stabilizer (wt. percent) oi v 1.4- Acrylo- Ethyl Nitro- Experiment (hexane mtrile acetate methane State of test piece Control 1 3. 0 0. 3 Whole of surface is black. 2 3. 0 0. 3 0.5 Major portion of surface is black. Example 1 3. 0 0. 3 O. 5 O. 3 About one-half of the surface is colored brown. 2 2- 5 0. 3 0. 5 0. 5 Do.

followed by thorough shaking and then resting. The upper layer is then taken and its pH value is determined with a pH meter.

TABLE 1 Stabilizer (wt. percent) oi- Aerylo- Ethyl Nitro- Experiment lA-dioxane nitrile acetate methane Acetonitrile added instead of acrylonitrile. Propyl acetate added instead oi ethyl acetate. Nitroethane added instead of nitromethane.

It can be seen from the results given in Tablets 1 and 2 that the stabilized 1,1,1-trichloroethane of the invention does not cause corrosion of aluminum, iron and brass in the test by heating under reflux and therefore demonstrates excellent stability.

As is apparent from Table 3, the four classes of stabilizers added to the 1,1,1-trichloroethane by acting synergistically impart a very excellent stability thereto even in the case of the presence of an excess of Water.

What is claimed is:

1. A stabilized composition consisting essentially of 1,1,1-trichloroethane and, as a stabilizer therefore, 0.1- 5.0 weight percent of 1,4-dioxane, 0.01-1.0 weight percent of acrylonitrile, -0.05-3.0 weight percent of ethyl acetate and 0.1-3.0 weight percent of nitromethane.

2. A stabilized composition consisting essentially of 1,1,1-trichloroethane and, as a stabilizer therefor, 1-4 weight percent of 1,4-dioxane, 0.1-0.5 Weight percent of acrylonitrile, 0.1-1.0 weight percent of ethyl acetate and 0.1-1.0 weight percent of nitromethane.

TABLE 2.HEATING-UNDER-REFLUX CORROSION TEST Aluminum Iron Brass v1 tal' Metalm pH of liquid Metal m pH of liquid 1 e m pH of liquid Vapor Vapor Vapor Experiment Liquid phase Before After Liquid phase Before After Liquid phase Before After 6.0 3.7 O 6.0 5.5 6 iii 8 2 6.1 4.7 2 x 6.1 3,5 0 5.9 5.1 O A 6 6 5. 8 213 8 8 518 514 A x 5.8 51 Example: 5.0 5.8 0 O 5.9 5.6 1 8 i iii 8 8 2.2 2 2 8 8 2.3 8 213 8 8 519 517 o 0 519 1 References Cited UNITED STATES PATENTS 3,445,532 5/ 1969 Richtzenhain et al.

260-6525 R 3,060,125 10/1962 Sims 260-652.5 R 3,113,155 12/1963 Sims 260652.5 3,661,788 5/1972 Campbell et a1. 260652.5 X 3,049,571 8/1962 Brown 260652.5 R 3,251,891 5/1966 Cormany et al. 260'652.5 R 3,505,415 4/1970 Richtzenhain et al.

260'-652.5 R 3,265,747 8/1966 'Cormany et al. 260-652.5 R 3,128,315 4/1964 Hardies 2 260652.5 R 3,326,989 6/1967 Cormany et a1. 260'-652.5 R

Primary Examiner U.S. Cl. X.R. 

1. A STABILIZED COMPOSITION CONSISTING ESSENTIALLY OF 1,1,1-TRICHLOROETHANE AND, AS A STABILIZER THEREFOR, 0.15.0 WEIGHT PERCENT OF 1,4-DIOXANE 0.01-1.0 WEIGHT PERCENT OF ACRYLONITRILE 0.05-3.0 WEIGHT PERCENT OF ETHYL ACETTE AND 0.1-3.0 WEIGHT PERCENT OF NITROMETHANE. 